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SHEEP (symbolic Computation System)
SHEEP is one of the earliest interactive computer algebra system, symbolic computation systems. It is specialized for computations with tensors, and was designed for the needs of researchers working with general relativity and other theories involving extensive tensor calculus computations. SHEEP is a freeware package (copyrighted, but free for educational and research use). The name "SHEEP" is pun on the Lisp Algebraic Manipulator or ''LAM'' on which SHEEP is based. The package was written by Inge Frick, using earlier work by Ian Cohen and Ray d'Inverno, who had written ALAM - Atlas LISP Algebraic Manipulation in earlier (designed in 1970). SHEEP was an interactive computer package whereas LAM and ALAM were batch processing languages. Jan E. Åman wrote an important package in SHEEP to carry out the Cartan-Karlhede algorithm. A more recent version of SHEEP, written by Jim Skea, runs under Cambridge Lisp, which is also used for REDUCE (computer algebra system), REDUCE. See also ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Computer Algebra System
A computer algebra system (CAS) or symbolic algebra system (SAS) is any mathematical software with the ability to manipulate mathematical expressions in a way similar to the traditional manual computations of mathematicians and scientists. The development of the computer algebra systems in the second half of the 20th century is part of the discipline of "computer algebra" or "symbolic computation", which has spurred work in algorithms over mathematical objects such as polynomials. Computer algebra systems may be divided into two classes: specialized and general-purpose. The specialized ones are devoted to a specific part of mathematics, such as number theory, group theory, or teaching of elementary mathematics. General-purpose computer algebra systems aim to be useful to a user working in any scientific field that requires manipulation of mathematical expressions. To be useful, a general-purpose computer algebra system must include various features such as: *a user interface allo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tensor
In mathematics, a tensor is an algebraic object that describes a multilinear relationship between sets of algebraic objects associated with a vector space. Tensors may map between different objects such as vectors, scalars, and even other tensors. There are many types of tensors, including scalars and vectors (which are the simplest tensors), dual vectors, multilinear maps between vector spaces, and even some operations such as the dot product. Tensors are defined independent of any basis, although they are often referred to by their components in a basis related to a particular coordinate system; those components form an array, which can be thought of as a high-dimensional matrix. Tensors have become important in physics because they provide a concise mathematical framework for formulating and solving physics problems in areas such as mechanics ( stress, elasticity, quantum mechanics, fluid mechanics, moment of inertia, ...), electrodynamics ( electromagnetic ten ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
General Relativity
General relativity, also known as the general theory of relativity, and as Einstein's theory of gravity, is the differential geometry, geometric theory of gravitation published by Albert Einstein in 1915 and is the current description of gravitation in modern physics. General theory of relativity, relativity generalizes special relativity and refines Newton's law of universal gravitation, providing a unified description of gravity as a geometric property of space and time in physics, time, or four-dimensional spacetime. In particular, the ''curvature of spacetime'' is directly related to the energy and momentum of whatever is present, including matter and radiation. The relation is specified by the Einstein field equations, a system of second-order partial differential equations. Newton's law of universal gravitation, which describes gravity in classical mechanics, can be seen as a prediction of general relativity for the almost flat spacetime geometry around stationary mass ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freeware
Freeware is software, often proprietary, that is distributed at no monetary cost to the end user. There is no agreed-upon set of rights, license, or EULA that defines ''freeware'' unambiguously; every publisher defines its own rules for the freeware it offers. For instance, modification, redistribution by third parties, and reverse engineering are permitted by some publishers but prohibited by others. Unlike with free and open-source software, which are also often distributed free of charge, the source code for freeware is typically not made available. Freeware may be intended to benefit its producer by, for example, encouraging sales of a more capable version, as in the freemium and shareware business models. History The term ''freeware'' was coined in 1982 by Andrew Fluegelman, who wanted to sell PC-Talk, the communications application he had created, outside of commercial distribution channels. Fluegelman distributed the program via the same process as ''shareware''. As s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lisp Algebraic Manipulator
The Lisp Algebraic Manipulator (also known as LAM) was created by Ray d'Inverno, who had written Atlas LISP Algebraic Manipulation (ALAM was designed in 1970). LAM later became the basis for the computer package SHEEP
Sheep (: sheep) or domestic sheep (''Ovis aries'') are a domesticated, ruminant mammal typically kept as livestock. Although the term ''sheep'' can apply to other species in the genus '' Ovis'', in everyday usage it almost always refers to d ... .
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Ray D'Inverno
Ray or RAY may refer to: Fish * Ray (fish), any cartilaginous fish of the superorder Batoidea * Ray (fish fin anatomy), the bony or horny spine on ray-finned fish Science and mathematics * Half-line (geometry) or ray, half of a line split at an initial point * Directed half-line or ray, half of a directed or oriented line split at an initial point * Ray (graph theory), an infinite sequence of vertices such that each vertex appears at most once in the sequence and each two consecutive vertices in the sequence are the two endpoints of an edge in the graph * Ray (optics), an idealized narrow beam of light * Ray (quantum theory), an equivalence class of state-vectors representing the same state Arts and entertainment Music * The Rays, an American musical group active in the 1950s * Ray (musician), stage name of Japanese singer Reika Nakayama (born 1990) * Ray (girl group), a Japanese girl group formed in 2019 * Ray J, stage name of singer William Ray Norwood, Jr. (born 1981) * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interactive
Across the many fields concerned with interactivity, including information science, computer science, human-computer interaction, communication, and industrial design, there is little agreement over the meaning of the term "interactivity", but most definitions are related to Human–computer interaction, interaction between users and computers and other machines through a user interface. Interactivity can however also refer to interaction between people. It nevertheless usually refers to interaction between people and computers – and sometimes to interaction between computers – through software, hardware, and networks. Multiple views on interactivity exist. In the "contingency view" of interactivity, there are three levels: #Not interactive, when a message is not related to previous messages. #Reactive, when a message is related only to one immediately previous message. #Interactive, when a message is related to a number of previous messages and to the relationship between th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Batch Processing
Computerized batch processing is a method of running software programs called jobs in batches automatically. While users are required to submit the jobs, no other interaction by the user is required to process the batch. Batches may automatically be run at scheduled times as well as being run contingent on the availability of computer resources. History The term "batch processing" originates in the traditional classification of methods of production as job production (one-off production), batch production (production of a "batch" of multiple items at once, one stage at a time), and flow production (mass production, all stages in process at once). Early history Early computers were capable of running only one program at a time. Each user had sole control of the machine for a scheduled period of time. They would arrive at the computer with program and data, often on punched paper cards and magnetic or paper tape, and would load their program, run and debug it, and carry off thei ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jan E
Jan, JaN or JAN may refer to: Acronyms * Jackson, Mississippi (Amtrak station), US, Amtrak station code JAN * Jackson-Evers International Airport, Mississippi, US, IATA code * Jabhat al-Nusra (JaN), a Syrian militant group * Japanese Article Number, a barcode standard compatible with EAN * Japanese Accepted Name, a Japanese nonproprietary drug name * Job Accommodation Network, US, for people with disabilities * ''Joint Army-Navy'', US standards for electronic color codes, etc. * ''Journal of Advanced Nursing'' Personal name * Jan (name), male variant of ''John'', female shortened form of ''Janet'' and ''Janice'' * Jan (Persian name), Persian word meaning 'life', 'soul', 'dear'; also used as a name * Ran (surname), romanized from Mandarin as Jan in Wade–Giles * Ján, Slovak name Other uses * January, as an abbreviation for the first month of the year in the Gregorian calendar * Jan (cards), a term in some card games when a player loses without taking any tricks or scoring a mi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
REDUCE (computer Algebra System)
REDUCE is a general-purpose computer algebra system originally geared towards applications in physics. The development of REDUCE was started in 1963 by Anthony C. Hearn; since then, many scientists from all over the world have contributed to its development. REDUCE was open-sourced in December 2008 and is available for free under a modified BSD license on SourceForge. Previously it had cost $695. REDUCE is written entirely in its own Lisp dialect called Standard Lisp, expressed in an ALGOL-like syntax called RLISP that is also used as the basis for REDUCE's user-level language. Implementations of REDUCE are available on most variants of Unix, Linux, Microsoft Windows, or Apple Macintosh systems by using an underlying Portable Standard Lisp (PSL) or Codemist Standard Lisp (CSL) implementation. CSL REDUCE offers a graphical user interface. REDUCE can also be built on other Lisps, such as Common Lisp. Features * arbitrary precision integer, rational, complex and floating-po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
GRTensorII
GRTensorII is a Maple package designed for tensor computations, particularly in general relativity. This package was developed at Queen's University in Kingston, Ontario by Peter Musgrave, Denis Pollney and Kayll Lake. While there are many packages which perform tensor computations (including a ''standard Maple package''), GRTensorII is particularly well suited for carrying out routine computations of useful quantities when working with (or searching for) exact solutions in general relativity. Its principal advantages include *convenience of definition of new spacetimes and tensor expression *efficient computation with frames *efficient computation of Ricci and Weyl spinor components and of Petrov classification *efficient computation of the Carminati-McLenaghan invariants and other curvature invariant In Riemannian geometry and pseudo-Riemannian geometry, curvature invariants are scalar quantities constructed from tensors that represent curvature. These tensors are usually th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
